Elastomeric fibers, such as those made from polyurethane (e.g., spandex), possess outstanding stretch and recovery properties making them suitable for many types of fibers, fabrics, laminates and other articles. Elastomeric polyolefin fibers (e.g., lastol, Dow Chemical's XLA™, ExxonMobil's Vistamaxx™) also have good stretch properties but, due to low melting points, are not always suitable for end-use where the end-use article (e.g., apparel) will be subject to high heats (e.g., during laundering). Elastomeric propylene based polymer fibers retain the stretch properties of non-cross-linked elastomeric propylene fibers, but can withstand much higher temperatures, making them more suitable for certain applications, such as fabrics for apparel.
However, all of the above elastomeric fibers, such as spandex and elastomeric polyolefin fibers, are known to display increased tackiness as compared to conventional, inelastic fibers. Because of their increased tackiness, these elastomeric fibers may cohere to each other or alternatively adhere to various surfaces. High tackiness becomes especially problematic in packaging where the fiber is wound around a core to form a bobbin, cake, or other such yarn package. The close proximity of the fibers plus the pressure on the fibers, especially near the core, may cause adjacent pieces of filament to cohere to each other, leaving the effected filament unusable since the fibers can be difficult to remove from the wound package without breaking. This problem becomes even more pronounced at the core, and is referred to as “core waste”. After packaging, filament tackiness may increase during storage depending on time and temperature. Longer storage time and higher temperatures equate to increased tackiness and more core waste. Accordingly, a reduction in tackiness for elastomeric fibers would reduce core waste and increase cost effectiveness.
To reduce tackiness, a finish is applied to the yarn, such as spandex. These finishes can include silicon oil and metal stearates. The finishes are employed for lubricating the surfaces of elastomeric fibers and thus reducing the tackiness of the fibers. However, many such finishes, particularly silicone-based finishes interfere with downstream processing and render the treated fibers unsuitable for certain applications or require taking costly steps to remove the finish from the fibers. For instance, certain applications involve downstream processing that either necessitates no finish or where it is preferred to have no finish. In processes such as gluing heavy denier yarn into diapers and other disposable personal care articles, finish interferes with the adhesion of the glue to the fiber, resulting in less effective bonding of the elastomeric fiber and increased creep. Finish, particularly silicone-based finishes, can also interfere with fabric dyeing and finishing, thus necessitating costly and time-consuming steps to scour off the finish before dying and/or other downstream processing steps. However, such finishes are nearly uniformly employed in elastomeric fibers, since, as discussed above, fibers made with no finish are too tacky to unwind—breaking before they come off the spool. Even when anti-tack additives have been incorporated into spandex fibers to help reduce tackiness, surface finishes (such as finishing oils) are still required in order to prevent breakage and core-waste problems.
Thus, there is a need for improved elastomeric fibers, and fabrics and articles made therefrom, that possess reduced tack without the need for silicone-based finishes and processes for providing such fibers.